I agree that his point is valid for computers built on the ordinary substrate of classical switches (whether relays, tubes, or transistors). There are two very influential ways of representing computation, the lambda calculus and the Turing machine; when starting from switches, people (roughly) build something that looks like a Turing machine (with procedural programs) and then, if they want lambda calculus (with more functional programs) they use Turing completeness to emulate it.
That said, it's not 100% clear to me that this must be true for all physical models of computation. (And the existence of Shor's algorithm suffices to keep practical people at least a little interested in computational mechanisms which are fundamentally different from classical switches.) Does anyone know if there are any reasonably plausible computational mechanisms for which it'd be natural to start by implementing something that looked more like lambda calculus, so that if you needed a Turing machine you'd emulate it?
That said, it's not 100% clear to me that this must be true for all physical models of computation. (And the existence of Shor's algorithm suffices to keep practical people at least a little interested in computational mechanisms which are fundamentally different from classical switches.) Does anyone know if there are any reasonably plausible computational mechanisms for which it'd be natural to start by implementing something that looked more like lambda calculus, so that if you needed a Turing machine you'd emulate it?